Multiple unit mine cable cutter



March 14, 1967 M. KURTZ 3,308,781

MULTIPLE UNIT MINE CABLE CUTTER Filed Sept. 16, 1957 3 Sheets-Sheet 1 m' 05 (D L LL (\1 Q r0 \0 f I I I CD INVENTOR I MARK KURTZ I; W Mill I ATTORNEYS March 14, 1967 Filed Sept. 16, 1957 M. KURTZ 3,308,781

MULTIPLE UNIT MINE CABLE CUTTER 3 SheecIs-Sheet 2 ATTORNEYS March '34, W67 M. KURTZ 3,308,781

MULTIPLE UNIT MINE CABLE CUTTER Filed Sept. 16, 1957 3 Sheets-Sheet 5 BY @(4 2% FIG.

ATTORNEY United States Patent Navy Filed Sept. 16, 1957, Ser. No. 684,380 1 Claim. (Cl. 114-221) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention constitutes an improvement on the applicants invention disclosed in the patent application entitled Multiple Unit Mine Cable Cutter, Ser. No. 581,811, filed April 30, 1956, and relates to an underwater cable cutter actuated by explosive means, said cutter being adapted to sever the cable by which an explosive mine is anchored in the water.

Mine cable cutter devices are well known and usually are used in conjunction with sweep lines towed by minesweeping vessels. However, in the prior art the number of cutters than can be installed on a sweep line per unit length thereof is limited because individual cutters are spaced along the sweep line and each cutter is quite heavy. Consequently the number of mine anchor cables that can be cut per given length of sweep line is similarly limited, necessitating rearming of the cable cutters at frequent intervals, and impeding the rapid sweeping of an area heavily infested with explosive mines. An object of the invention is to overcome the foregoing and other disadvantages of the prior art.

An object of the invention is to provide a mine cable cutter or cutting tool of the explosive type which is light in weight, which is simple in construction, and which is improved in operation.

A further object of this invention is to provide a mine cable cutter design and arrangement which makes it possible to attach a greater number of the cutters to a given length of sweep line.

Still another object is to provide a mine anchor cable cutter with a fool-proof trigger mechanism actuated only upon contact with said cable.

In addition, it is an object of this invention to provide a cable cutter that is less subject to fouling due to underwater debris and the like than the prior art cutters, and which cannot be accidently discharged while the cutter is out of the water.

A still further object is to provide a cable cutter with an anvil member that is not likely to be broken away except upon discharge of the cutter mechanism.

It is an additional object to provide a cable cutter, of the type having an anvil member, with means whereby the cable cutter is discharged in the event that the anvil member is accidently broken away from the cutter.

Still another object is to provide a cable cutter mechanism that is simple in construction and that can be used repeatedly at little expense and with a minimum of effort and training.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a view showing a plurality of cutters made according to this invention and attached to a mine sweep line;

FIG. 2 is an end view of the assembly shown in FIG. 1 looking from the left;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 1;

FIG. 4 is a longitudinal sectional view of an individual cutter shown in loaded and cocked condition;

IFG. 5 is a side view of the cutter looking from the left in FIG. 4;

FIG. 6 is a sectional view of the cutter taken on line 66 of FIG. 4;

FIG. 7 is a sectional view of said cutter taken on line 77 of FIG. 4;

FIG. 8 is a vertical sectional view, partially broken away, of the upper portion of the cable cutter mechanism at the beginning of its cutting operation; and

FIG. 9 is a sectional view taken on line 9-9 of FIG. 8, but showing the cutting operation at a stage somewhat more advanced than that of FIG. 8.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a view of an assembly of four mine cable cutters or cutting tools 20 on a mine sweep line 22. It is pointed out that all of said cutters or tools are substantially identical.

As shown in FIG. 4, each cutting tool 20 comprises a frame 24. The part of said frame adapted to be located toward the far or trailing end of a sweep line has a cylindrical hole or barrel 26 formed therein; and a cutting chisel 28 is slidably mounted in said barrel. The chisel 28 comprises a cutting mechanism, and is held in fixed position by a shear pin 30 that passes through alignable holes in both the frame and the chisel. Extending from the lower end of the barrel is a chamber 32, said chamber being adapted to receive a cartridge 34 therein. The cartridge 34 is utilized to fire the cutting mechanism comprising the chisel 28 forwardly in a manner hereinafter set forth.

An anvil 36 is fastened to a forward part of the frame 24 and has a forward portion thereof spaced from and extending across the forward end of said barrel. The forward portion of the anvil 36 is adapted to confine a mine cable in a position to be struck andcut by the chisel 28 during operation of the cutter. The anvil 36 is provided with a shank member 38 at the rear thereof having a leading face 42 which is in line with one Wall of the barrel 26. The shank member is reduced in thickness near its lower end to provide a tenon that fits within a notch provided in the frame 24. The shank 38 is held onto the frame 24 by a screw-type shear pin 40 which passes through both the frame and said tenon as shown in FIG. 6, and is threaded in the shank only. The anvil member 36 is restrained against a tendency to rotate about shear pin 40, by virtue of the abutment of a lower portion of leading face 42 of the shank 38 against a side portion of the chisel 28, a shown in FIG. 4. The abutting surfaces of the anvil 36 and frame 24 have a substantial area of contact and are interlocked by the tenon and notch construction, so that accidental breaking away of said anvil from the frame by snagging or the like is unlikely. A further anti-snagging feature resides in the forward surface 48 of the anvil 36 being substantially flat and smooth so as also to avoid entanglement with an extraneous object.

The anvil 36 is in a sense hook-shaped with a leading face 50 inclined inwardly toward a recess 52 of the anvil 36 that faces the forward end of the frame 24. The inclined face 50 is adapted to guide a mine cable into the space between the recess 52 and the front end of the frame 24 for positioning a snared mine cable so that the cable can be cut by the cutting chisel 28 moving toward the anvil 36; said position being shown in FIG. 10 for example. The curved recess 52 helps to hold the mine cable in cutting position.

The mine cable is cut by the chisel 28 when the chisel is forced toward the anvil 36 by discharge of the cartridge 34 carried at the lower extremity of the frame 24. The

cartridge is discharged by firing mechanism located at the lower end of the frame. The firing mechanism comprises a breech block 54 having therein a bore 56 axially aligned with the chamber 32 in which the cartridge 34 is carried. The bore 56 is closed at the end thereof adjacent the cartridge chamber 32, except for a small hole 58 through which a firing pin 60 is adapted to move and strike the base of the cartridge 34. The lower portion of the firing pin 60 is provided with four laterally extending webs 62 arranged at right angles. The webs slidably engage the wall of the bore 56 below said small hole 58. The firing pin 68 is normally held in retracted position, as shown in FIG. 4, by a spring 64 compressed between the respective upper ends of the webs 62 and the forward end wall of the bore 56. Two oppositely disposed webs 62 extend rearwardly to a pivotal connection 66 with one end of a lever 68 located in a slot 70 in the breech block 54. Intermediate its ends said lever is pivotally connected to said breech block by a pivot pin 72. The lever 68 and breech block are provided with aligned holes 74 through which a safety rod or pin 76 may be passed for latching the lever against pivoting about pivot pin 72 so as to prevent accidental firing of the mechanism by accidental pivoting of said lever 68. The other end of the lever 68 has a piston 78 pivotally connected thereto which extends forwardly in a cylinder 80 in the breech block 54, said piston being slidable within said cylinder. The cylinder 80 is located at the side of the breech block opposite the bore 56 and is parallel therewith. Thus it will be seen that a rearward movement of the piston 78 will bring about the firing of the cartridge by rotating the lever 68 about its pivot and forcing the firing pin 60' forwardly against the cartridge 34.

The breech block 54 is held in contact with a rear end of the main frame 24 of the cutter by being fastened to a side extension 82 of said frame, said extension having a turned rear end portion 84 abutting the rearmost portion of the breech block, as indicated in FIGS. 4 and 5. The breech block is removably attached to the frame by a screw 86 threaded into a hole in the extension 82.

In axial alignment with but spaced from the piston cylinder 80, the frame 24 of the cutter is further provided with a plunger 88 having a rear end portion adaptedito enter the cylinder 80. The plunger 88, however, cannot move far enough to contact the piston 78. When the assembly is submerged in water, water fills the remaining space in the cylinder 80 in which the piston 78 is situated, and thus rapid rearward movement of the plunger 88 into the cylinder 80 forces water against the piston. The force of the moving plunger 88, acting through the water, forces the piston 78 rearwardly, thereby moving the firing pin 60 forwardly against the cartridge 34, discharging the latter. The explosion drives the chisel member 28 toward the anvil 36 for cutting action.

In order to prevent fouling of the piston cylinder 80 by underwater debris, a hole 90 is provided in the under wall of the frame to insure a free flow of water past the mouth of the cylinder, when the tool is submerged.

The plunger 88 has a sleeve 92 rigidly fixed thereto adjacent its forward end, said sleeve and plunger being slidable in a passage 94 having the same shape as said sleeve, for example, hexagonal. A collar 96 having a central hole is snugly mounted in the plunger passage to properly guide the plunger and insure proper alignment thereof with the piston cylinder 80. The collar 96 is carried in a slot in the frame 24, the collar having a shoulder 98 at one end to further limit movement thereof.

The rearmost end of the cylindrical plunger 88 slides within the circular opening provided in said collar.

A rod 100 is fastened to the forward face of the sleeve 92 and extends forwardly across a recess 102 in the side of the cutter frame 24. The rod 100 has a forward end slidably mounted in a hole 104 provided in a protrusion in the forward part of the frame. The forward end of the rod 100 has a hole 106 therein extending transversely of the axis of the rod for a purpose hereinafter set forth. One or more springs 108 surround the rod and are normally under compression between the sleeve 92 and the under surface of the said protrusion, thereby tending to urge the plunger 88 rearwardly toward the piston.

The plunger 88 is normally held in retracted position against the action of the springs 108 by means of a wirelike, S-shaped trigger pin 110, FIG. 4. The rearmost leg 111 of the trigger pin normally is partially situated within a tranverse groove 112 provided in the forward end of the frame 24. It is pointed out that the groove '112 has an enlarged portion 113 at that end thereof adjacent to the barrel 26 that carries the chisel 28. The rearmost leg 111 of the trigger pin 118 that normally lies in the groove 112 has an offset portion situated within the enlarged portion 113 of the groove whereby that part of the rearmost leg portion that crosses the barrel 26 is offset with respect to the axis of the chisel member; as better shown in FIG. 6. The rearmost leg 111 of the trigger pin is provided with a smaller latching element or extension 114 at its free end, said extension being adapted to enter the hole 106 in the forward end of the rod 100, thereby retaining said rod in retracted position, against the action of spring 108, in the manner shown in FIG. 4.

The rearmost leg 111 of the trigger pin extends across the opening in which the chisel 28 is carried to a point substantially adjacent the face 42 of the shank portion 38 of the anvil 36, said shank portion adjacent the trigger pin being provided with a cut-away area 116 that is deeper than the thickness of the trigger pin. At the portion of the trigger pin adjacent the shank member 38, the trigger pin is provided with a bend at substantially right angles to leg 111, and thence to provide an intermediate cross portion that extends toward the hook portion of the anvil. The cross portion extends to another right angle bend in the pin 110; and from this bend the pin has a forwardmost leg 117. The forwardmost leg 117 of the trigger pin 110 is long enough to extend into a hole 118 that extends transversely of the shank member 38, said hole being of a diameter that is greater than the maximum thickness of the leg 117 of the trigger pin. The free end of the leg portion 117 is provided with a threaded end portion 121, whereby an internally threaded retaining cap 123 may be screwed onto the end of said leg portion 117 in the manner shown in FIG. 8. The retaining cap 123 is provided with a head portion that is somewhat larger in diameter than the diameter of the hole 118. In assembling the instant cutter, the trigger pin 110 is installed in the cutter in the manner shown in FIG. 7, with the forwardmost leg 117 in hole 118, after which time the cap member 123 is screwed onto the threaded portion 121 of the leg portion 117.

The combination of the retaining cap 123 with the trigger pin 110 serves not only to retain the pin in proper position, but also serves as a safety device. It is pointed out that in the event that the hook-shaped member 36 should become snagged on some underwater object other than 'a mine cable and be accidentally broken away from the cutter assembly, the hook member will come to bear against the head portion 125 of the cap 123 and in pushing against said head portion will withdraw the extension 114 on the trigger pin 110 from the rod 1011 thereby causing the cutter to be discharged in the manner hereinafter described. It is pointed out that if the retaining cap 123 were not used, the breaking away of the hook member 36 might leave the trigger pin in its normal position. Thus when such a cutter is retrieved aboard ship it is quite likely that someone may inadvertently withdraw the trigger pin from locking position, thereby discharging the cutter in the event that foreign matter or water happens to be retained in the cylinder 80. This of course raises the possibility of grave injury to a crew member or the like. It has been found that in the absence of the hook member 36, while the cutter is being towed under water, it is quite unlikely that a mine cable will strike only the trigger pin exposed from the forward end of the cutter, hence there is no great loss in discharging the device upon the accidental breaking away of a hook member 36.

It is pointed out that the trigger pin 110 is prevented from turning in the frame by virtue of the offset portion of the rearmost leg being located in the enlarged area 113 in the forwardmost portion of the frame.

The narrower extension 114 at one end of the pin 110 provides a shoulder 119 that in cocked position of the cutting tool as shown in FIG. 4 abuts the top part of the rod 104, so that the movement of the pin 110 will be guided at the start when the cutting tool is submerged in water and a mine cable line such as 120 is snared.

Assuming that the cable line 120 is snared, the face 50 of the tool cams'the line toward the recess 52 in the anvil 36. The line strikes the trigger pin 110 and in the manner shown in FIGS. 8 and 9, pushes the trigger pin toward the shank 38 of the anvil. The extension 114 leaves the hole 106 in the rod member 100, permitting the coil springs 108 to drive the plunger 88 rearward toward the breech block 54 and towards the cylinder 80 in which the piston 78 is located. The water in said cylinder is pushed by the plunger and being incompressible drives the piston rearwardly, rocking the lever 68 about pin 72, thereby driving the firing pin 60 forwardly. The forwardly moving pin 60 discharge the cartridge 34 so that the chisel 28 is forcefully driven forwardly toward the anchor line 120 and the anvil 36. As the chisel moves forwardly, one of its beveled surfaces strikes an edge of the offset portion of the trigger pin in the manner shown in FIG. 9, thereby turning the trigger pin about its forward leg 117 in hole 118, and also tilting it forwardly as shown in broken lines in FIG. 9. It is pointed out that the rearmost leg 111 of the trigger pin is pushed far enough forward to clear the upper side edges of the groove 112, as shown in FIG. 8, so that the face of the chisel may rotate the trigger pin completely out of the path of the chisel in the manner shown in FIG. 10. The chisel will not strike the forwardly extending portion of the trigger pin because the movement of the cable line 120 forces said portion itno the recessed area 116 in the shank of the anvil, as shown in FIG. 8. After cutting the cable, the edge of the chisel strikes the anvil 36. The drive of the chisel is adequate to cut the cable and shear off the screw 40, and thus break the anvil away from the frame. Thus it can be seen that when a cutter is fired, the 'anvil is lost, thereby preventing the snagging of another mine cable by a cutter that has already been fired. The lost anvil can readily be replaced with another one for rearming the cutter when the sweep line is hauled in. It is pointed out that accidental discharge of the cutter tool by underwater debris or the like's triking the trigger pin, is prevented by virtue of the fact that the anvil is substantially thicker than the trigger pin and hence acts as a shield therefor, as can be seen in FIG. 5.

In the event that the trigger pin is accidently removed from hole 106 prior to placing the device underwater so that passage 94 is air-filled, the plunger will not strike the piston, as the movement thereof will be stopped when the sleeve 92 strikes the collar 96 contained within the plunger passage 94. This stopping position is reached before the plunger 88 reaches piston 78. As a further precaution, the aligned holes provided in the lever 68 within the breech block and in the cover of the breech block are adapted to receive the safety pin 76 that will prevent rotation of said lever. Prior to placing the mechanism within the water, the safety pin is withdrawn.

One advantage of the structure described above is that it results in a compact, light-weight cable cutter, wherein the parts are so arranged as to make possible the use of a greater number of such cutters per given length of mine sweep line. Specifically, the above described cutter has approximately one-fourth the weight of the standard cutter used heretofore, and shown in Patent No. 2,422,- 506. One arrangement of cutters on a sweep line is shown in FIG. 1 wherein four cable cutters are shown attached to a single conventional carrier member, said carrier member being clamped to a sweep line 22. The cutter at the extreme left is shown in discharged condition with its anvil lost or spent.

The carrier consists of a base plate 122 having afiixed thereto a stabilizing fin 124 extending laterally therefrom, said fin member being adapted to maintain the combination of cutters in a horizontal plane as they are swept through the water. A U-shaped member having a crosspiece 126 and legs 130 is carried by the base plate. The crosspiece 126 is afiixed to, and extends lengthwise of, said base plate 122, and the rearmost ends of the respective cable cutters abut said crosspiece and are bolted thereto by bolts 1 28 extending into holes in the end portions 84. The legs 130 extend outwardly of the base plate 122 adjacent the forward end thereof. The forward leading edge of the base plate 122 is also provided with a flange 131 extending outwardly therefrom and adapted to deflect a mine anchor cable into the path of one of said hooks.

The first cable cutter abuts a leg 130 as well as the longitudinal crosspiece 126, the various cutters being placed in abutting relation to one another, as shown in FIG. 1. The base plate 122 is adapted to be attached to the sweep line 22 by means of two or more U-shaped clip members 132 in the manner shown in FIG. 2, a toggle bolt 134, extending through the legs of said U- shaped member and the base plate with the cable being located between said bolt and the bite of the U-shaped clamp.

The compact arrangement shown in FIG. 1 is made possible not only by virtue of the compactness of each cutter and its light weight, but also by the fact that each cutter is so oriented on the base plate 122 that when said base plate is attached to the mine sweep line 22 said cutter extends substantially at right angles to said sweep line. As a result of orienting the cutters in the manner described above each anvil 36 is so arranged that its hook portion faces lengthwise of the sweep line instead of transversely thereof as has been the case heretofore. Consequently, the cutters successively become active for mine cable cutting operations. It is further pointed out that the shank of one anvil is in abutting relation with the frame of an adjacent unfired cutter and hence when a chisel strikes the anvil, said anvil will be driven forwardly and then away from the cutter frame, thus preventing same from striking any adjacent anvil and thus preventing accidental dislodgement of another anvil. With the last cutter of the group, this precaution is not essential.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

What is claimed is:

A mine cable cutter comprising an elongated frame, a barrel provided in said frame adjacent one side thereof and opening at one end of said frame; a hook-shaped member attached to the frame adjacent said end, said hook-shaped member comprising a shank portion attached to said frame and extending forwardly thereof, said hook-shaped member further comprising an anvil portion extending from said shank portion across and spaced from the adjacent end of said frame, thereby forming a mine cable receiving recess between said anvil and said frame, a cutting member slidably mounted in said barrel, explosive means for forcibly driving said cutting member across said cable receiving recess and against said anvil; actuating means for discharging said explosive means, an S-shaped trigger-pin having a first arm releasably engaged with said last means for retaining said means in an inoperative position, and a second arm extending transversely of said recess and longitudinally of the path of travel of said cutting member at substantially right angles to said first arm, said second arm being adapted to be moved by a mine cable as said cable moves through said recess whereby said trigger-pin is released from said actuating means, whereby said explosive means is discharged, said triggerpin further comprising a third arm afiixed to one end of said second arm and extending at substantially a right angle to said arm, said third arm extending into a hole formed in said shank portion, said third arm being provided with a threaded end portion located within the hole in said shank member, an internally threaded cap member extending into the hole in the shank member from the side of the shank opposite that from which the third arm enters said shank, said cap member being screwed onto the threaded end portion of said third arm and being provided with an enlarged head portion of a width larger than the maximum Width of the hole in said shank member, thereby locking said trigger-pin against removal from the hole in said shank member.

References Cited by the Examiner Temple 89- 1 MILTON B'UCHLER, Primary Examiner. SAMUEL BOYD, Examiner. S. W. ENGLE, Assistant Examiner. 

